Related Experiment Video
Updated: Jun 25, 2026
Non-Invasive Compression-Induced Anterior Cruciate Ligament (ACL) Injury and In Vivo Imaging of Protease Activity in Mice
Published on: September 29, 2023
Proximal Calf Muscle Cross-Sectional Area After Anterior Cruciate Ligament Reconstruction: A Longitudinal MRI
Harvi F Hart1,2,3, Brooke E Patterson3, Hayden F Atkinson2
1Department of Kinesiology, College of Education, Michigan State University, East Lansing, MI, USA.
Context:
Weakness of the quadriceps and hamstrings often persists following rehabilitation after anterior cruciate ligament reconstruction (ACLR). Yet, recovery of the gastrocnemius muscle following ACLR remains unclear. Thus, we aimed to compare the cross-sectional areas (CSAs) of the calf (lateral and medial gastrocnemius) muscle in individuals 1 year after ACLR with uninjured controls and to investigate longitudinal CSA changes up to 5 years post-ACLR.
Design:
Secondary analysis of a longitudinal cohort study.
Methods:
Existing knee MRI axial scans of 78 individuals, 1 year after ACLR, and 17 uninjured controls were segmented to obtain lateral and medial gastrocnemius muscle CSAs. Follow-up MRIs at 5 years post-ACLR were also segmented. Cross-sectional areas were compared in participants 1 year post-ACLR and controls using analysis of covariance, adjusting for age, sex, and body mass index. Changes in CSAs from 1 to 5 years post-ACLR were evaluated using paired t tests. Supplementary analyses included sex-stratified analyses.
Results:
Individuals 1 year after ACLR had smaller lateral gastrocnemius muscle CSA than controls (mean difference: -3.86 cm2; 95% CI, -5.71 to -2.00), but no differences were found in the medial gastrocnemius muscle CSA (-1.02 cm2; 95% CI, -2.95 to 0.91). Lateral (0.54 cm2; 95% CI, -0.18 to 1.27) and medial (0.30 cm2; 95% CI, -0.43 to 1.03) gastrocnemius muscle CSA did not change between 1 and 5 years post-ACLR. The supplementary analyses revealed increases in both lateral (0.85 cm2; 95% CI, 0.24-1.47) and medial (0.53 cm2; 95% CI, 0.16-0.90) gastrocnemius muscle CSAs in females from 1 to 5 years post-ACLR, but not in males.
Conclusion:
Calf muscle atrophy exists 1 year after ACLR, suggesting that postoperative rehabilitation should target muscles beyond the thigh. Moreover, sex-specific changes in calf muscle size over time underscore that muscle size recovery may differ by sex.